Process for the distillation of mixed substances of which soap is a constituent



Patented Nov. 29, 1932 UNITED STATES PATENT OFFICE WILHELM GENSECKE, OF GONZENHEIM NEAR FRANKFORT-ON-THE-MAIN, GERMALlY PROCESS FOR THE DISTILLATION OF MIXED SUBSTANCES OF WHICH SOAP IS A CONSTITUENT No Drawing. Application filed 0ctober24, 1929, Serial No. 402 ,322, and in Germany October 31, 1928.

This invention relates to a process for the distillation of mixed substances of which soap is a constituent. It is particularly adapted for the distillation of mixtures consisting of a solvent for oil and soap, although the invention is not restricted thereto. Such mixtures occur for example in oil refining. The fattyacid soaps (soapstock) obtained in such cases as residue contain considerable quantities of neutral oil, the separation of which, as completely as possible, from the soap is recognized as a noteworthy problem. It has already been proposed to separate the oil from the fatty-acid soap by means of solvents and then subject the separated miscella (solvent with dissolved oil) to distillation, and also to distill the soap (which contains some of the solvent) separately, for the purpose of expelling the solvent. This proposal, however, has not led to any practically successful results. Although it is known that there is nodiificulty in expelling the solvent from the miscella, it has been found, on the other hand, impracticable to separate the solvent from the fatty-acid soapby distillation, chiefly on account of the extensive frothing of the soap.

According to the invention, this can now be accomplished if the fatty-acid soap in the mixture of solvent and soap be reconverted into fatty acid prior to distillation, for example by decomposition with mineral acid. The distillation can then be effected without difiicult j The fbllowing examples for the practical application of the inventional idea will serve to explain the invention more fully.

1. Treatment of neutralization residues (soap stock) which may, for example, contain 50% of soap and 50% of neutral oil. In such case the various stages of the treatment are as follows (1) A solvent which substantially dissolves the neutral oil alone is added to the soapstock.

(2) The miscella formed by the solution of the oil is separated (so far as is possible) from the soapstock by decantation.

(3) The miscella still retained by the soapstock is expelled therefrom by the passage of more solvent; that is, the soapstock is washed with the solvent.

(4) The miscella obtained by'decantation in stage (2) is separated into solvent and neutral oil by distillation; and the same occurs with the miscella obtained in stage (3) by washing the soapstock with solvent. The

two miscellae could, of course, also be distilled jointly. 1

(5) The'soapstock obtained in stage (3) and now containing only solvent, is decomposed with mineral acid, the soap being thereby transformed into fatty acid.

(6) The resulting fatty acid is separated from thecsolvent by. distilling oif the latter.

The residual fatty acid may either be utilized as a final product, or, if thevpresence of ,pig- L mentary and other impurities render it de- I sirable, may be freed from these impurities by distillation.

The treatment prior to distillation can also be appliedto the treatment of oils and fats obtained by extraction with solvents. Such oils and fats, which always contain a larger or smaller amount of fatty acids, have hitherto always been treated by first distilling off the solvent and then subjecting the-residual oil to the same several rocesses as are employed in the case of oi s and fats obtained Other mixtures also can be distilled in accordance with the invention. For example,

water can be distilled off or evaporated; odorous substance of a pleasant or disagreeable character can be eliminated by distillation and so forth.

Ewample 500 kgs. of fatty-acid soap, originating from the neutralization of the free fatty acids of ground-nut oil by means of sodium carbonate solution (Na CO and containing about 40% of neutral oil, are placed in a vesselprovided with stirrers, which are set in active motion while 3000 kgs. of benzol, at 30 C. are added. After the soap and solvent have become thoroughly mixed, the stirrers are stopped, and the contents of the vessel are left at rest. Two layers separate out, the lower one consisting of a mixture of fatty acid soaps and miscella, and the upper one of a solution of neutral oil in benzol. This layer is decanted, and the solvent is expelled from the neutral oil by distillation in known manner. The fatty-acid soap is treated with solvent a second time-and a third time if necessary-in order to extract the neutral oil therefrom as completely as possible.

The extracted soap, "which still contains large quantities of solvent, is dissolved in a. sevenfold ,quantity of warm water, whereupon an amount of sulphuric acid equal to 20% in excess of that required for the decomposition of the fatty acid soap is added with energetic stirring. The mixture is then warmed, with further active stirring, where; by the fatty acid is liberated from the soap; and the heating of the contents of the vessel is carried so far as to distil olf the benzol present, the vapours of the solvent being deposited in a condenser. After all the solvent has been expelled from the fatty acid, the

stirring and heating are discontinued, and.

the mixture is allowed to rest, the fatty acid separating out, in a well defined manner, from the acid liquor. The latter is drawn off first, and then the solvent-free fatty acid.

Example I I 2000 kgs. of miscella (solvent and rape-oil solution), obtained by extracting crushed seed with benzol and containing about 30% of oil, are placed in a closed vessel provided After the free fatty acid is neutralized, the

stirring is discontinued, and the contents of v the vessel are left at rest. "Two layers are formed, a lower layer consisting of a mixture of rape-oil fatty acid soaps and miscella, and over this a layer of neutral oil dissolved in benzol. The upper layer is decanted, and the miscella is separated into solvent and neutral oil by distillation in known manner.

The mixture of rape-oil soap and miscella is treated with a fresh quantity of solvent or with a dilute miscella, in order to remove the neutral oil.

The extracted fatty-acid soap, which still soaps, separating the soaps from the solution of oil, and washing the soaps with said oil solvent until they are substantially free of neutral oil, the improved method of removing the said oil solvent remaining in admixture with soap from said mixture which comprises converting the fatty acid soaps in the mixture into free fatty acids and thereafter removing the oil solvent from the mixture by distillation.

. 2. In the refining of mixtures of neutral oils and free fatty acids by treating a solution of the oil in a solvent for oil which is a non-solvent for soaps with a neutralizing agent to convert the free fatty acid into soaps, separating the soaps from the solution of oil and washing the soaps with said oil solvent until they are substantially free of neutral oil,

from said mixture which comprises adding water to the mixture, converting the fatty acid soaps in the mixture into free fatty acids and thereafter removing the oil solvent from the mixture by distillation.

3. In the refining of mixtures of neutral oils and free fatty acids by treating a solution of the oil in asolvent for oil which is a non-solvent for soaps with a neutralizing agent to convert the free fatty acid into soaps, separating the soaps from the solution of oil and washing the soaps with said oil solvent until they are substantially free of neutral oil, the improved method of removing the said oil solvent remaining in admixture with soap from said'inixture which comprises adding suflicient water to the mixture to form an aqueous solution of the fatty acid soaps, converting the fatty acid-soaps in the mixture into free fatty acids and thereafter removing the oil solvent from the mixture by distillation.

- In testimony whereof, I afix my signature.

WILHELM GENSECKE. 

